位数不足补0

NSString *str = [NSString stringWithFormat:@"%02zd点",n];
//  e.g:  %02zd -->05       %03zd-->005

获取汉字拼音

- (NSString *) pinyinFirstLetter:(NSString*)sourceString {
    
    NSMutableString *source = [sourceString mutableCopy];
    CFStringTransform((__bridge CFMutableStringRef)source, NULL, kCFStringTransformMandarinLatin, NO);
    CFStringTransform((__bridge CFMutableStringRef)source, NULL, kCFStringTransformStripDiacritics, NO);   // 这一行是去声调的
    
    NSLog(@".....>> %@",source);
    
    return source;
}

首字母大写

NSString *str = @"abcdefghijklmn";
    NSString *resultStr;
    if (str && str.length > 0) {
        resultStr = [str stringByReplacingCharactersInRange:NSMakeRange(0,1) withString:[[str substringToIndex:1] capitalizedString]];
    }
    NSLog(@"%@", resultStr);

字符串开头、结尾

if([str hasPrefix:@"http"]){ 

} 

if([str hasSuffix:@".com"]){ 

} 

长按复制

[self.view addGestureRecognizer:[[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(pasteBoard:)]];
}
- (void)pasteBoard:(UILongPressGestureRecognizer *)longPress {
    if (longPress.state == UIGestureRecognizerStateBegan) {
        UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
        pasteboard.string = @"需要复制的文本";
    }

判断String是否包含某字符串

[str containsString:@"abc"];
或
NSString *women = @"Hey  you are boy?";
if ([women containsString:@"boy"]) 

/*--->字符串开头 是否含有某字符串
if ([string hasPrefix:@"hello"]) {

/*--->字符串末尾 是否有某字符串
if ([string hasSuffix:@"bitch"]) {

取单个字符

// 取第i个字符
NSString *chara = [string substringWithRange:NSMakeRange(i, 1)];

字符串反转

- (NSString *)reverseWordsInString:(NSString *)str
{    
    NSMutableString *newString = [[NSMutableString alloc] initWithCapacity:str.length];
    for (NSInteger i = str.length - 1; i >= 0 ; i --)
    {
        unichar ch = [str characterAtIndex:i];       
        [newString appendFormat:@"%c", ch];    
    }    
     return newString;
}
或
- (NSString*)reverseWordsInString:(NSString*)str
{
    NSMutableString *reverString = [NSMutableString stringWithCapacity:str.length];
    [str enumerateSubstringsInRange:NSMakeRange(0, str.length) options:NSStringEnumerationReverse | NSStringEnumerationByComposedCharacterSequences  usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
    [reverString appendString:substring];
}];
    return reverString;
}

判断字符串是否为空

+ (BOOL)isEqualToNil:(NSString *)str {
    return str.length <= 0 || [str isEqualToString:@""] || !str;
}

- (BOOL)isExist {
    NSString *str = [self stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
    return (str.length != 0);
}

或 
使用宏定义：
#define Validity_Str(string) (((string != nil) && (string.length>0))?YES:NO)    // 判断字符串是否有效

在文字中添加表情

//emoji 表情，只需在label的text中加上“\u+表情代码”即可。如：
aLabel.text = @"今天天气非常好\uE337";

附：表情代码大全（取Unicode编码的代码，如：U+1F604-->U0001F604）
http://punchdrunker.github.io/iOSEmoji/table_html/index.html

判断输入的 是否汉字

- (BOOL)isHasChineseWithStr:(NSString *)strFrom {
    
    for (int i=0; i<strFrom.length; i++) {
        
        NSRange range =NSMakeRange(i, 1);
        NSString * strFromSubStr=[strFrom substringWithRange:range];
        const char *cStringFromstr = [strFromSubStr UTF8String];
        
        if (strlen(cStringFromstr)==3) {
            //汉字
            return YES;
        } else if (strlen(cStringFromstr)==1) {
            //字母
        }
    }
    return NO;
}

分隔字符串，分隔成n个元素的数组

NSString*string =@"sdfsfsfs-dfsdf";

NSArray *array = [string componentsSeparatedByString:@"-"]; 
NSLog(@"array:%@",array); 
//结果是adfsfsfs和dfsdf

汉字编码

NSstring *str = [chineseName stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];

去掉HTML标签

-(NSString *)filterHTML:(NSString *)html
{
    NSScanner * scanner = [NSScanner scannerWithString:html];
    NSString * text = nil;
    while([scanner isAtEnd]==NO)
    {
        [scanner scanUpToString:@"<" intoString:nil];
        [scanner scanUpToString:@">" intoString:&text];
        html = [html stringByReplacingOccurrencesOfString:[NSString stringWithFormat:@"%@>",text] withString:@""];
    }
    return html;
}

动态计算字串宽度、高度

// 动态计算文本宽度
+ (CGFloat)widthWithText:(NSString *)text andFontSize:(CGFloat)fontSize{
    CGRect rect =
    [text boundingRectWithSize:CGSizeMake(SCREEN_WIDTH, MAXFLOAT)
                       options:NSStringDrawingUsesLineFragmentOrigin
                    attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]}
                       context:nil];
    return rect.size.width;
}

// 动态计算文本高度
+ (CGFloat)heightWithText:(NSString *)text andFontSize:(CGFloat)fontSize{
    CGRect rect =
    [text boundingRectWithSize:CGSizeMake(SCREEN_WIDTH - 100, MAXFLOAT)
                       options:NSStringDrawingUsesLineFragmentOrigin
                    attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize]}
                       context:nil];
    return rect.size.height;
}

计算字符串字符长度，一个汉字算两个字符

-(NSUInteger) unicodeLengthOfString: (NSString *) text
{
    NSUInteger asciiLength = 0;
    for (NSUInteger i = 0; i < text.length; i++)
    {
        unichar uc = [text characterAtIndex: i];
        asciiLength += isascii(uc) ? 1 : 2;
    }
    return asciiLength;
}

字符串base64编码

+ (NSString *)base64StringFromText:(NSString *)text {
    
    NSData *data = [text dataUsingEncoding:NSUTF8StringEncoding];
    NSString *base64String = [data base64EncodedStringWithOptions:0];
    return base64String;
}
/*  解码 */
+ (NSString *)textFromBase64String:(NSString *)base64 {
    
    NSData *data = [[NSData alloc] initWithBase64EncodedString:base64 options:0];
    NSString *text = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    
    return text;
}

字符串解码

NSString *result = [url stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

对字符串进行UTF-8编码：输出UTF-8格式

[str  stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]]；

字符串编码

NSString *urll = self.URL;
    urll = [urll stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet characterSetWithCharactersInString:@"%<>[\\]^`{|}\"]+"].invertedSet];

// 我们一般用这个方法处理stringByAddingPercentEscapesUsingEncoding但是这个方法好想不会处理／和&这种特殊符号，这种情况就需要用下边这个方法处理
@implementation NSString (NSString_Extended)
- (NSString *)urlencode {
    NSMutableString *output = [NSMutableString string];
    const unsigned char *source = (const unsigned char *)[self UTF8String];
    int sourceLen = strlen((const char *)source);
    for (int i = 0; i < sourceLen; ++i) {
        const unsigned char thisChar = source[i];
        if (thisChar == ' '){
            [output appendString:@"+"];
        } else if (thisChar == '.' || thisChar == '-' || thisChar == '_' || thisChar == '~' || 
                   (thisChar >= 'a' && thisChar <= 'z') ||
                   (thisChar >= 'A' && thisChar <= 'Z') ||
                   (thisChar >= '0' && thisChar <= '9')) {
            [output appendFormat:@"%c", thisChar];
        } else {
            [output appendFormat:@"%%%02X", thisChar];
        }
    }
    return output;
}

字典转字符串

SData *jsonData = [NSJSONSerialization dataWithJSONObject:dic options:NSJSONWritingPrettyPrinted error:&parseError];

NSString * str = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

json字符串转字典

+ (NSDictionary *)dictionaryWithJsonString:(NSString *)jsonString
{
    if (jsonString == nil) {
        return nil;
    }
    
    NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
    NSError *err;
    NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData
                                                        options:NSJSONReadingMutableContainers
                                                          error:&err];
    if(err)
    {
        NSLog(@"json解析失败：%@",err);
        return nil;
    }
    return dic;
}

模型数组转json字符串

    //先模型数组 转 字典数组
    NSArray *dictArray = [PDcycleImageItem mj_keyValuesArrayWithObjectArray:_extraCycleImgArray];

    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dictArray options:NSJSONWritingPrettyPrinted error:nil];
    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

字符串替换

NSString*str =@"12345678";
NSString*Str2 = [str stringByReplacingOccurrencesOfString:@"345"withString:@"543"];

去除所有的空格、换行

可解决JSON字符串格式错误问题。

+ (NSString *)removeSpaceAndNewline:(NSString *)str {
    NSString *temp = [str stringByReplacingOccurrencesOfString:@" " withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    return temp;
}

字符串拼接相关

1. 如果count不足2位 用0在最前面补全(2代表总输出的个数)
NSInteger count = 5;
NSString *string = [NSString stringWithFormat:@"%02zd",count];
//输出结果是: 05
2. 加百分号%
NSInteger count = 50;
//%是一个特殊符号 如果在NSString中用到%需要如下写法
NSString *string = [NSString stringWithFormat:@"%zd%%",count];
//输出结果是: 50%
3. 含双引号：如果在NSString中用到"需要用\进行转义
NSInteger count = 50;
NSString *string = [NSString stringWithFormat:@"%zd\"",count];
//输出结果是: 50"

获取字符串中的数字

    NSString *ssstr = @"额发发哦342.5范文芳个人房贷";
    NSCharacterSet* nonDigits =[[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    float num =[[ssstr stringByTrimmingCharactersInSet:nonDigits] floatValue];
    NSLog(@" num %.1f ",num);

截取某个字符串之后的字符串

      NSRange range = [aString rangeOfString:@"redirect="]; //现获取要截取的字符串位置
      NSString *rurl = [aString substringFromIndex:range.location]; //截取字符串 
//--返回结果包含该字符串 ：redirect=

截取两个指定字符串中间的 字符串

    NSString *string = @"<a href=\"http\">这是要截取的内容</a>";

    NSRange startRange = [string rangeOfString:@"\">"];
    NSRange endRange = [string rangeOfString:@"</"];
    NSRange range = NSMakeRange(startRange.location + startRange.length, endRange.location - startRange.location - startRange.length);
    NSString *result = [string substringWithRange:range];
    NSLog(@"%@",result);

获取字符串中的URL

正则表达式 的应用

+ (NSArray *)getURLFromString:(NSString *)string {
    
    NSError *error;
    //可以识别url的正则表达式
    NSString *regulaStr = @"((http[s]{0,1}|ftp)://[a-zA-Z0-9\\.\\-]+\\.([a-zA-Z]{2,4})(:\\d+)?(/[a-zA-Z0-9\\.\\-~!@#$%^&*+?:_/=<>]*)?)|(www.[a-zA-Z0-9\\.\\-]+\\.([a-zA-Z]{2,4})(:\\d+)?(/[a-zA-Z0-9\\.\\-~!@#$%^&*+?:_/=<>]*)?)";
    
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regulaStr
                                                                           options:NSRegularExpressionCaseInsensitive
                                                                             error:&error];
    
    NSArray *arrayOfAllMatches = [regex matchesInString:string
                                                options:0
                                                  range:NSMakeRange(0, [string length])];
    
    NSMutableArray *arr=[[NSMutableArray alloc] init];
    
    for (NSTextCheckingResult *match in arrayOfAllMatches){
        NSString* substringForMatch;
        substringForMatch = [string substringWithRange:match.range];
        [arr addObject:substringForMatch];
    }
    return arr;
}

截取指定范围的子串

NSString *str = @"今天天气真不错，是风和日丽的，我们下午没有课，是心情也不错";
        
    // 从x位置开始，到最后结束,包括x
    NSString *str1 = [str substringFromIndex:17];

    //从开始位置到指定位置x，不包括x
    NSString *str2 = [str substringToIndex:7];

    // 某个范围内
    NSRange range = {7, 10};
    NSString *str3 = [str substringWithRange:range];
        
    NSRange range1 = [str rangeOfString:@"我们下午没有课"];
    NSString *str4 = [str substringFromIndex:range1.location];

    //从某个字串的位置开始，到结尾
    NSUInteger loc1 = [str rangeOfString:@"/"].location + 1 ;
    NSString *result = [str substringFromIndex:loc1];

设置label富文本

// 创建Attributed  
NSMutableAttributedString *noteStr = [[NSMutableAttributedString alloc] initWithString:_label.text];  
// 改变的区间 
NSUInteger firstLoc = [[noteStr string] rangeOfString:@"金"].location + 1;  
NSUInteger secondLoc = [[noteStr string] rangeOfString:@"元"].location;   
NSRange range = NSMakeRange(firstLoc, secondLoc - firstLoc);
// 改变颜色  
[noteStr addAttribute:NSForegroundColorAttributeName value:[UIColor greenColor] range:range]; 
// 改变字体大小及类型  
[noteStr addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Helvetica-BoldOblique" size:27] range:range];   

[_label setAttributedText:noteStr];    // 为label添加富文本 属性

改变指定子串的颜色等

NSString *str0 = @"今天天气非常的好，我们去玩吧，好不好。";
            
NSMutableAttributedString *attributedStr = [[NSMutableAttributedString alloc] initWithString:str0];

NSRange range0 = [str0 rangeOfString:@"非常的好"]; 

[attributedStr addAttribute:NSForegroundColorAttributeName value:MainThemeBlue range:range0]; 
             
_contentLb.attributedText = attributedStr;

文字中添加图片

    //先实例化一个Lable
     ... ... 
  
    // 创建一个富文本
    NSMutableAttributedString *attri = [[NSMutableAttributedString alloc] initWithString:@"超时罚款24元/小时"];
    //  创建NSTextAttachment对象，用来装图片
    NSTextAttachment *attch = [[NSTextAttachment alloc] init];
    attch.image = [UIImage imageNamed:@"parking_caveat_normal"];
    attch.bounds = CGRectMake(0, 0, 15, 15);

    // 创建带有图片的富文本
    NSAttributedString *string = [NSAttributedString attributedStringWithAttachment:attch];

     // 在文字后面添加图片
    [attri appendAttributedString:string];
    或
    // 在文字下标第几个添加图片  
    [attri insertAttributedString:string atIndex:0];   //0就是文字前添加图片

    // 用label的attributedText属性来使用富文本
    lable.attributedText = attri;

持续更新中... ...